The long-term objective is to implement a personal-computer based system supporting volumetric data registration and other tasks required in the analysis of volume data such as PET, MRI, XCT, etc. The system will combine the convenience and ease-of-use characteristics of personal computers with network capabilities exploiting data storage and computational services typically available at medical institutions. Benefits resulting from increased access to volume data, evocative visual presentations, and solution of the registration problem when multiple data volumes are involved will be valuable in both clinical and research settings. The specific aims of Phase I are (1) develop and test a prototype system, and (2) develop new algorithms to support the fast rendering of images representing arbitrary slices through a volume. The methodology will include the use of a mature graphical user interface development environment, visual metaphors based on arbitrary planar slices to provide visual access to 3D data, and efficient pixel-based rendering strategies. Innovations include (1) efficient algorithms that make it possible to render arbitrary slices in near real time, (2) visual metaphors and user-interface protocols needed to facilitate interactive registration, and (3) the creation of an architecture supporting user-extensibility and exploiting database and computational services available via network.